Can you split multi-gpus with multi psu's?

J

jfharper

Limp Gawd
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Mar 25, 2005
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I'm looking at building a 3d animation workstation with multi gpus to help with real time rendering. Instead of plugging in all th gpus into the MB, I would plug only the card(s) needed for the monitors, and use riser/extender boards for the additional gpus. The large psu's and corresponding ups are expensive. If I ran a second psu for just a couple cards, would this work? I'm thinking I'd need that tester thing plugged into the second psu, power that on first, then power the psu for the MB last? Could i effectively use two 1000 watt psu like this, or one 1000 watt and one 800 watt? Perhaps have them plugged into separate smaller and cheaper ups's?

Maybe I'm not thinking this out correctly, and the cost would be the same in the end...
 
I don't see why not. A PSU is just powering the system/components. I'm positive I've seen this (multi PSU's) done, somewhere, before. Maybe over on OCnet.
 
Just how many cards are you trying to run at once here? I've got 3 980 Ti's in a single rig running 100% 24/7 with a single 1200W PSU. It's also a 6-core Intel CPU that's running 100% load 24/7 as well. No issues at all.

Though to answer your question what Chas posted is right on the money.
 
Skillz said:
Just how many cards are you trying to run at once here? I've got 3 980 Ti's in a single rig running 100% 24/7 with a single 1200W PSU. It's also a 6-core Intel CPU that's running 100% load 24/7 as well. No issues at all.

Though to answer your question what Chas posted is right on the money.
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4-6... when I putting a 3d scene together, and creating materials and adjusting lights, have the real time rendering helps speed this up...vray rt gpu mode works with multiple gpus, so 4-6 might work well.

I would probably run one card in the MB to run my monitors, then the rest with a 1x pcie adapter riser...the other cards are not for any on demand graphical output, only to speed up rendering. I'm open to suggestions and corrections on my thinking...I'm still learning all this.
 
Use your onboard GPU to power your monitors and use riser cards for everything else. If you don't have an onboard GPU, get a few of those USB 3.0 to VGA/DVI/Displayport adapters and save the motherboard slots for as many GPUs as you can fit.
 
jfharper said:
4-6... when I putting a 3d scene together, and creating materials and adjusting lights, have the real time rendering helps speed this up...vray rt gpu mode works with multiple gpus, so 4-6 might work well.

I would probably run one card in the MB to run my monitors, then the rest with a 1x pcie adapter riser...the other cards are not for any on demand graphical output, only to speed up rendering. I'm open to suggestions and corrections on my thinking...I'm still learning all this.
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Well if you can swing it, what I'd do is buy a pro system designed to handle all those GPUs. Supermicro makes some bigass systems that'll take 4 or more GPUs (as done nVidia themselves). At work we buy from Nor-Tech who is a Supermicro integrator/reseller. It'll cost you more than trying to hack something together, but work better. They come with multiple slottable PSUs (up to 3 I've seen) to deal with heavy loads.

I think you might find that a 1x PCIe extension would work like crap, if at all. If at all because I don't think cards can actually share PCIe lanes. It is a point-to-point interface. So you'd need something that provides at least a lane per card, and divides those lanes up properly. Even if you do get that set up, I think you might find that the bandwidth would be an issue. I mean you are talking about handing off a lot of geometry/materials data to a card and then getting a result back, that needs a lot of bandwidth.

So I'd look at a heavy hitter system instead. Either an nVidia VCA or Supermicro.

Also remember if you are talking really bigass power requirements, you need separate power circuits. You hook two 1500 watt PSUs to the same 15amp line, you'll drop a breaker. You need a full separate circuit for each PSU, or a larger capacity one like 30+amps.
 
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